汽车工程

汽车工程 ›› 2019, Vol. 41 ›› Issue (12): 1370-1376.doi: 10.19562/j.chinasae.qcgc.2019.012.004

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逆流式混合器的设计及尿素结晶风险评估方法研究

韩峰1, 张晓丽1, 王意宝1, 胡晓艳1, 王霞1, 石代龙2   

  1. 1.潍柴动力股份有限公司发动机研究院,潍坊 261205;
    2.山东大学,济南 250061
  • 发布日期:2019-12-25
  • 通讯作者: 张晓丽,工程师,E-mail:zhangxiaoli@weichai.com

Study on Counterflow Mixer Design and Urea Crystallization Risk Assessment Method

Han Feng1, Zhang Xiaoli1, Wang Yibao1, Hu Xiaoyan1, Wang Xia1, Shi Dailong2   

  1. 1.Engine Research Center, WEICHAI Power Co., Ltd., Weifang 261205;
    2.Shandong University, Jinan 250061
  • Published:2019-12-25

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摘要： 传统双层管SCR混合器在排气温度低的工况易在混合器壁面形成尿素结晶。为解决此问题,设计了一种新型逆流式SCR混合器及其与喷嘴座的集成布置方案。利用CFD技术和台架试验相结合验证了逆流式混合器的预防尿素结晶能力和对NOx排放的影响,并对尿素结晶机理及尿素结晶风险评估方法进行了深入研究,提出了基于“尿素结晶能量因子”比较不同工况尿素结晶风险的方法。对逆流式SCR催化器进行台架瞬态排放测试试验和30 h发动机台架尿素结晶验证试验,台架试验结果表明:逆流式结构混合器的瞬态NOx转化率提高了1.8%,30 h台架尿素结晶试验表明逆流式混合器壁面未出现尿素结晶。

关键词: 逆流式混合器, 尿素结晶, 能量因子法, CFD技术

Abstract: Urea crystallization is easy to form on the wall of traditional double-tube SCR mixer at low exhaust temperature condition. In order to solve this problem, a new type of counter-flow SCR mixer and its integrated layout scheme with nozzle seat are designed in this paper. By combining CFD technology and bench test, the anti-urea crystallization ability of the counterflow mixer as well as its influence on NOx emission is verified. The mechanism and risk assessment of urea crystallization are studied in depth. The method based on urea crystallization Excess Energy Ratio (EER) is proposed to compare urea crystallization risk under different operating conditions. The emission test in transient state and 30 h engine bench test on urea crystallization of the counterflow SCR catalytic converter are conducted. The bench test results show that the transient conversion efficiency of nitrogen oxides of the counter-flow mixer has increased by 1.8% while the 30 h bench test results show that no urea crystallization appear on the wall of the counter-flow mixer.

Key words: counter-flow mixer, urea crystallization, excess energy ratio, CFD technology